This invention relates to internal combustion engines, and more particularly to improved sealing apparatus between a cylinder block and a cylinder head of a motorcycle engine.
As is well known, internal combustion engines such as motorcycle engines include a cylinder block having a combustion chamber bore (generally referred to as a cylinder bore) intermediate a cylinder head and a crank-case, with sealing gaskets being provided at the interfaces between the head and block and between the block and case. In particular, a gasket is conventionally provided between the block and the head (generally referred to as a "head gasket") of a Harley-Davidson motorcycle engine for sealing the combustion chamber compression gasses from leakage at the interface of the bottom end surface of the head and the top end surface of the block. The head gasket additionally seals against fluid leakage at the head/block interface, from fluid passages in the head and in the block communicating between the head and block. One such fluid passage in a Harley-Davidson motorcycle engine is for returning oil from the head through the block and to the crank-case.
One type of head gasket for a Harley-Davidson motorcycle engine is described in U.S. Pat. No. 4,836,158, to Ignatius J. Panzica, which patent is incorporated herein by reference. The head gasket therein disclosed is intended as an improved replacement for the original-equipment Harley-Davidson head gasket which is later described herein.
In situations where it may be desired to modify the motorcycle block, such as by enlarging the cylinder bore to accommodate a piston of increased diameter, prior art head gasket configurations with dimensional modifications are generally used. However, there exists a need to provide more effective sealing at the head/block interface than is provided by modified prior art head gaskets in such situation.